Logged in as student and edited his profile. Added a homepage url - www.uct.ac.za
Log in as instructor, go to Roster tool, click Profile of student then click on his homepage url. Received the following error
type Status report
description The requested resource (/sakai-roster-tool/www.uct.ac.za) is not available.
Go back and change the URL to http://www.uct.ac.za - not error. Link open fine in new window.